Sri Lanka's Tamil Tiger rebels have written to European cease-fire monitors, denying responsibility for recent killings that have been blamed on the Tigers and threaten to plunge the country back into civil war.

In a letter posted Sunday on the Tigers' Web site, the rebels accused the government and military of trying to discredit them by assassinating people who might appear to be likely targets of the guerrillas.

Rising violence in Sri Lanka's northeast "points to a systematically planned and timed orchestration to discredit the LTTE (Liberation Tigers of Tamil Eelam)," the Tigers wrote, using their group's official name.

Scores of people _ including many of the Tigers' political opponents _ have been killed in the past several weeks in the country's northeast, where the rebels have long had a strong presence. The victims have included school teachers, shop owners and religious leaders.

The government and military have blamed the Tigers for the violence, despite both sides having signed a Norway-brokered cease-fire in 2002. On Sunday, military spokesman Brig. Nalin Witharanage brushed off the rebels' letter and denied that the military was behind the killings.

Officials from Norway, Sweden, Denmark, Finland and Iceland have been monitoring Sri Lanka's cease-fire since it was signed in February 2002. The monitors' chief, Hagrup Haukland, said he received the letter and intends to reply, but did not reveal what he plans to say.

The Tamil Tigers started fighting the government in 1983 to try creating a separate state for the country's ethnic minority Tamils, accusing the majority Sinhalese of discrimination. More than 65,000 people were killed in the conflict before the cease-fire. The truce has stalled due to disagreements over postwar power-sharing, and many in Sri Lanka fear the continuing violence could cause the country to slide back into war, AP reports.